Telangana SCERT Class 8 Physical Science Chapter 8 Solution – Combustion fuels and flame. Here in this post we provides Class 8 Physical Science Combustion fuels and flame Telangana State Board Solution. Telangana State Board English Class VIII Medium Students can download this Solution to Solve out Improve Your Learning Questions and Answers.
Telanagana State Board Class 8 Physical Science Chapter 8 Combustion fuels and flame Solution:
(1) Give four examples of combustible materials.
Ans: – Wood, paper, petrol, cotton cloths etc.
The material which burn when brought near a flame, they are called combustible material.
(2) Why should not we store spirit or petrol near our living place?
Ans: – In the lowest temperature at which a substance catches fire is called its ignition temperature. Petrol or spirit has low ignition temperature. The ignition temperature decides quickness of catching fire. Petrol or spirit are also called inflammable substances, because and easily catch fire, very soon. So it’s very dangerous to store such inflammable substances. So we should not store spirit or petrol near our living place.
(3) The oil fires should not be sprayed with water. Why?
Ans: – Water is not suitable for fires involving oil and petrol, because water is heavier than the oil, it sinks below the oil and oil keeps burning on the top. So it is difficult to remove the combustible material from a fire.
(4) Water is not used to control fires involving electrical equipment. Why?
Ans: – The most common fire extinguisher is water. But water works only when things like wood cloth and paper are n fire. If electrical equipment is on fire water may conduct electricity and harm those trying to douse the fire.
(5) List the ways adopted by fire fighters to combat fires.
Ans: – If fire breaks out in a house or in any place, business establishment the fire freighter will immediately put of electric mains and then start spraying water on the fire.
Carbon dioxide gas is the best choice used to combat fires. It can be stored as a liquid in cylinders under high pressure.
Using sand can be useful to combat fire.
(6) Draw the diagram of candle flame and label all the zones.
Application of concepts
(1) What precautions are to be taken while pouring water on fire?
(i) Do not pour water on fires due to petrol and oil because water is more denser than oil and petrol.
(ii) Put of all the electric mains.
(iii) Call the fire engine immediately.
(2) Give an example of a good fuel. How do you choose that fuel? Explain.
Ans: – The example of good fuel is CNG
I will choose that fuel because –
(i) It should be get in different and availability.
(ii) It should be easy to handle
(iii) It should be get in reasonable price.
(iv) It should be easy to handle
(v) It should be easy to ignite and put off
(vi) It should be easy to transport
(viii) This fuel should burn at a moderate rate and cause less pollution
(ix) It should have a high calorific value.
(3) It is difficult to burn a heap of green leaves but not a heap of dry leaves. Explain why?
Ans: – It is difficult to burn a beep of green leaves because of a large quality of water is present, for this it can’t burn. But on the other hand dry leaves don’t contain such water. So their ignition temperature is low. So they burn during summer.
(4) Where do you find spontaneous combustion and rapid combustion in your daily life?
(i) Turn on the knob of the gas stove in the kitchen and bring a burning match stick or a gas lighter neat it. The gas burns rapidly and produces heat and light. Here we find rapid combustion.
(ii) The burning of kerosene oil in kerosene stove also a rapid combustion.
(i) Forest fire can also be started by spontaneous combustion reaction due to the heat of the sun or due to the spark lightning from the sky.
(5) Why the fire brigade start the work by putting off the electric mains?
Ans: – The fire brigade start the work by putting off the electrical mains because water is a good conductor of electricity and. So it they does not off the electrical mains, can get a electrical shock. When they handling the situation.
Higher Order Thinking Questions
(1) Why Phosphorus preserved in water?
Ans: – Phosphorus preserved in water because it is very reactive in air, so it catches fire easily when it comes to contact with air. Phosphorus has ignition temperature means it’s easily catches fire, so it is kept in water that it doesn’t react.
(2) How do you feel about “Fuels have become a part of human life”?
Ans: – Fuels are uses for different purpose at home, in automobiles and in industries, to cook food we are using fuels, because we are getting energy from food. Fuels give us electrical power makes us to live comfortable. So without fuels there is no human life. This fuel have become a major part of human life as we uses or needed fuel for many purpose. That’s why fuels firm play a major role of our human life.
(3) Is there any other procedure to prove that oxygen is needed for burning?
Ans: – Yes.
Now you light two candles an one you keep inside a glass and one out free. Now you see the one kept inside the glass that candle flame shed off because of lack of oxygen supply. But which candle is out free, it does not let off, because of oxygen supply properly.
(4) In a few years the fuels on earth will be exhausted. Think, what would happen to human civilization?
Ans: – In a few years the fuels on earth will be exhausted, so human need to search for alternative sources like solar energy, wind energy, which are not exhausted.
I think it is very difficult to live without fuels for people on earth. They faces a huge problems It also a huge loss for human civilization and their future generations.
So, bio-gas/bio-fuels and natural gas are also another source to use.
Multiple Choice Questions
(1) The gas needed for combustion among the following
Ans: – (b) Oxygen
(2) The lowest temperature at which a substance catches fire is called its
Ans: – (a) Ignition temperature
(3) The units of calorific value is
Ans: – (c) Kilojoules/kg
(4) Spirit and petroleum turns into gas at
Ans: – (a) Room temperature
(5) The type of combustion in which material suddenly burns into flames without the application of any external agent is called
Ans: – (c) Spontaneous combustion